I want to experiment with concentrating the alcohol in my beer by freezing the water in it, thus leaving behind a higher alcohol brew. Does anyone know of a way to determine what the ideal temp would be to maximize water freezing, but minimize alcohol freezing?

I understand that many mega breweries make ice beers, but their beers didn't have much on flavor from the start, so who cares what happens in the freezing process. The questions I have is when you freeze the water and extract it, are you going to take the flavor out as well? It seems that you are distilling in reverse. Most ice beer drinkers(I know, because I used to be one), drink the ice beer, because the alcohol gives you some taste of something other than corn water.

Yeah fitz, I wonder that to. I think there is a possibility of losing flavour. I imagine the water will freeze some of the compounds that make beer taste so good inside of the big ice block that will form. But, as you mention, this sort of reverse distillation is really what I am interested in. I want to try and generate a real hum-dinger of a brew that will knock my socks off. Real distilling is too complex for me to get in to right now, so I guess you could say I am going throught the back door with this one.

I would think that you would want to start with a high octane beer then. If you don't, you wont have much in the way of a finished product. after all, a 6% beer would only have approximately 7 to 7 1/2 ounces of alcohol to a gallon so a standard 5 gallon batch would be 35 ounces of alcohol. If you are going for the alcohol in its purest form, you may do some research on the ethanol side to make sure you won't have any of it in the freezing process. I know if you distill, the ethanol comes off the first portion of the "run" and you discard it. Otherwise, that stuff can make you sick or worse. I hear that you can make a distiller out of a pressure canner and some length of copper tubing. of course with this approach you are removing the alcohol first, with your approach, you would be removing the water. Check the ethanol bit though.

Your points are well taken. After my last post I was considering that my beer is generallly 5-6% alc/vol, so yeah, you are right that I would not get much in the way of volume if I removed a good portion of the water. I would think though that removing enough water to get a 15-20% alc/vol would be interesting. I think though that optimizing a system to do this would be tricky, and that the resulting beverage may be, as you noted, a little thin on flavour. I think this will be a thing I will experiment with, along wiht a few other ideas I have regarding unique grains and herb beers. thanks for the input.

A Belgian triple can give you a 10% + alcohol.
They aren't usually hoppy, but the alc. bite picks up the slack. I wondered about the condesning of the hop oils too. I know someone whom has a still(shhhh) it is illegal in the states. Anyway, I wondered if some of the not optimal beers wouln't make an excellent shine, but didn't know about the hops in the boil-off.
Sipping A good shine is hard to beat on a cold Jan. or Feb. day.

It is possible that even though some flavor is lost to the ice you still will get more concentrated flavor. It is possible that the amount of flavor compounds that you loose will be drastically offset by the removal of much of the water. Thus you will get a more concetrated beer flavor, of course as discussed above the opposite is also possible, i.e. that much of the flavor will be carried away with the ice.

An interesting calculation might be to find the compounds that most affect taste. I would guess that the list would include 2 classes of compounds. One class would be those compounds that are most abundant in beer. The other class would be those compounds that are commonly found in beer, but are not neccessarily abundant,and are easily perceived even at small levels by the tongue. I would imagine that you could find a database somewhere that would tell you whether or not these compounds are soluable in water or alcohol. Those that are not soluable in alcohol MAY not be PERCEIVED in the final product if a SIGNIFICANT amount of water is removed. I am not a chemist, but am rather good at rambling.

I think that others have hit all the high points on this one. The freezing point calculator would be a nice thing to have but it seems unecessary. I know from experience that pure alcohol will not freeze even down to dry ice temperatures. The freezing point of ethyl alcohol is -117.3oC. So bringing the temperature of the beer down below 32f will allow the water to freeze separating it from the alcohol. I have heard that this may decrease flavor of the beer some what due to falvor compounds being removed with the water crystals but I can't really say for sure how much of a change in flavor freezing will cause.

I have heard from others that have tried to freeze distill that you either need to freeze very slowly or freeze the beer completley and allow it to slowly warm up. See below.

Put the mash in a plastic jug, leaving enough room for expansion, then put this in the freezer until it's a solid block of ice, then invert the container over a collection jar and gather everything that melts out until you have collected half of what is in the jug. With a 10% mash, this will come out to about 17% ABV.

One last thing about Ice beers. The big beer makers freeze distill the beers and filter them during this process to remove the ice crystals and harsh flavor compounds. Then to avoid paying taxes on the distilled beer like it was wiskey they add back filtered water. I have heard that the law allows only 0.5% difference by vol. in order not to have to pay a tax.

See ATF ruling
ATF Ruling 94-3

The definition of "beer concentrate" in 27 CFR 25.11 does not include a beer whose volume has been reduced as long as there is not more than a 0.5 percent by volume reduction in the beer, and the resultant product retains its character as beer.

ATF has been asked whether the removal of a small quantity of water from beer renders that beer a concentrate under 25.11 and Subpart R of regulations in 27 CFR Part 25. This question has arisen as a result of the process used by some brewers in making ''ice beer."

Background. Beer is defined at 26 U.S.C. 5052 as "Beer, ale, porter, stout, and other similar fermented beverages (including sake or similar products) of any name or description containing one-half of one percent or more of alcohol by volume, brewed or produced from malt, wholly or in part, or from any substitute for malt."

27 CFR 25.11 defines concentrate as "Concentrate produced from beer by the removal of water under the provisions of Subpart R of this part." This section further states that the processes of concentration and reconstitution of beer are authorized processes in the production of beer.

Section 25.261 authorizes the production of concentrate from beer, and the reconstitution of beer from concentrate, at the brewery. Concentrate may be transferred without payment of tax between breweries of the same ownership and may be removed from the brewery without payment of tax for export. This section does not provide for the removal of concentrate from the brewery subject to tax.

Not as scientific a response as other, but from my experience drinking mass produced ice beers, for some reason seemed more likely to get a "beer headache".
Didn't always notice as taste difference. i.e. Butt ice pretty much taste as bad as buttwiper.
Although scientifically unsure how to say or explain, in my opinion some of the "stuff" removed when making an ice beer also takes "other stuff" or leaves behind a higher concentrate of oils or whatnot that would cause you to experience a "beer headache" when you normally wouldn't.
That's with 6-9% usually. What kind of effect might the 15-20% you mentioned have?
Also don't know how this would or wouldn't pertain to homebrew, where we don't usually pasturize and such, but perhaps someone else could explain it more scientifically.

The Ice beer headache may be due to the fact that when low alcohol solutions are heated during normal distillation only ETOH is separated (as well as other compounds that boil at 78.5C or lowered). The other higher order alcohols and fusel alcohols are left behind because they evaporate at a higher temperature. However, in freeze distillation all forms of alcohols are concentrated. So the compounds that cause bad hangovers are still present in the ICE beer. But then again the ice beer headache could be because it just bad beer to begin with... And I thought that most Ice beers are not pasturized rather they are 'cold filtered' which, given a fine enough filter, would remove the bacteria that would spoil the beer.

I would agree that most 'Ice Beers' (save the Eisenbocks) are pretty much worthless.

I would think that working to ice distill higher percentage alcohol brews might exasterbate the ice beer headache effect. Given that yeast may be stressed to produce more fusel alcohols during the fermentation of high sugar beers and then these 'bad' alcohols are concentrated during the freezing process one might want to use a lager strain like WLP885 or allow the concentrated beer to mature for a while before consuming.